A dark money group that blends environmentalism, population control advocacy, and anti-immigrant sentiment is running attack ads against House Speaker Paul Ryan in the Wisconsin Republican’s district.

The group, Californians for Population Stabilization (CAPS), is currently running ads in Milwaukee attacking Ryan for his position on “mass immigration.” It also established a website spotlighting the ad and accusing Ryan of “giving away the American dream.”

Despite his hesitance to endorse presumptive Republican presidential nominee Donald Trump, Ryan is easily beating a primary challenge from Wisconsin businessman Paul Nehlen. But the high-profile race has thrust immigration, a Trump campaign pillar, into the contest for Wisconsin’s first congressional district.

The CAPS ad illuminates a frequently overlooked connection between environmental and anti-immigration policies and the activists behind them. The group is one of several advancing restrictive immigration policies under the banner of conservation and natural resource preservation.

The group is run by California academics and environmentalists—its chairman holds a leadership position in a Bay Area chapter of the Sierra Club—but it melds concern about climate change and other environmental issues with a deep hostility to immigration and overpopulation.

The group “advocates slowing mass immigration to more sustainable levels and a deliberate approach to family size,” its website says. “It’s our government’s irresponsible immigration policy that to this day continues to import millions of people with little to no regard” for its financial or environmental impacts.

The ad in Wisconsin features Frank Morris, the executive director of the anti-immigration Center for Immigration Studies and the former executive director of the Congressional Black Caucus Foundation.

The ad does not mention Ryan by name, but it shows an image of the House Speaker as Morris says, “it’s time our leaders use some common sense and stood up for us.”

According to ad buy data filed with the Federal Communications Commission, the CAPS ad has been airing in Milwaukee since the middle of May on local and national ABC-affiliated news programs.

The group also reported running anti-immigration ads on Des Moines, Iowa, television stations last year.

The group did not respond to questions about its issue advocacy activities.

Trump has earned some kind words from CAPS’ staff members.

“Every politician in America must take note of the amazing success that Donald Trump has scored in advocating the commonsense position on immigration that the majority of Americans favor, irrespective of political orientation,” wrote CAPS senior fellow Michael Cutler last year.

The group does not disclose its donors—the names of its three 2014 contributors, who donated a total of $675,000, are redacted on its most recent tax filing—but filings by its institutional supporters provide a window into its financial backing.

One of its donors is the Foundation for the Carolinas, a $1.2 billion grantmaking group that in 2014 donated more than $165 million to environmental groups.

The foundation supported the Natural Resource Defense Council, the Sierra Club, the League of Conservation Voters, the Rainforest Action Network, and billionaire Democrat Tom Steyer’s NextGen Climate in addition to CAPS.

The largest funder of CAPS is the Colcom Foundation, a Pittsburgh-based group founded by the late Mellon family heiress Cordelia Scaife May. The Colcom Foundation has donated more than $4.6 million to CAPS since 1999.

“Her worry in life, almost, was population control,” a friend of May’s told the Los Angeles Times in 2013. “She loved animals almost more than people.”

Another CAPS funder, the Weeden Foundation, is run by Don Weeden, a strident environmentalist who sees mainline environmentalism as too focused on human well-being. The foundation has donated more than $350,000 to CAPS since 2001.

“A trend we see in the environmental philanthropic community somewhat, and within the environmental movement overall, has been a slow movement away from protecting biodiversity for its own sake and a bit toward conservation that has human ends,” Weeden told Inside Philanthropy last year.

“We need to see a lowering of consumption in developed countries, and we also need to bring down global population growth rates as soon as possible,” Weeden added.

According to its website, “Weeden Foundation board and staff members … have been, or are currently, board members of numerous environmental organizations including the Audubon Society, Sierra Club Foundation,” and other prominent green groups.

Weeden is also an executive at the anti-immigration group Numbers USA. That group was among a handful of groups that sparked controversy at April Earth Day festivals in Texas.

The Austin chapter of the Sierra Club withdrew from an event in that city, citing participation in a related event by Numbers USA and Progressives for Immigration Reform, a group run by Morris.

However, for CAPS and its funders, those goals are not just related but mutually reinforcing.

“Cultivating support among environmental and population organizations for [a restrictive immigration] policy is among our top grantmaking priorities,” according to a since-deleted page on Weeden’s website. Its policy goal, the website said, is to “promote immigration reduction on the basis of environmental concerns.”